[llvm] 7c7f467 - [LICM] Fix a crash when sinking instructions w/token operands

[Philip Reames via llvm-commits]

Author: Philip Reames
Date: 2021-03-17T11:18:46-07:00
New Revision: 7c7f4676cd421b1d64145eebfed11e5a3d8935d7

URL: https://github.com/llvm/llvm-project/commit/7c7f4676cd421b1d64145eebfed11e5a3d8935d7
DIFF: https://github.com/llvm/llvm-project/commit/7c7f4676cd421b1d64145eebfed11e5a3d8935d7.diff

LOG: [LICM] Fix a crash when sinking instructions w/token operands

It is not legal to form a phi node with token type. The generic LCSSA construction code handles this correctly - by not forming LCSSA for such cases - but the adhoc fixup implementation in LICM did not.

This was noticed in the context of PR49607, but can be demonstrated on ToT with the tweaked test case. This is not specific to gc.relocate btw, it also applies to usage of the preallocated family of intrinsics as well.

Differential Revision: https://reviews.llvm.org/D98728

Added: 
    

Modified: 
    llvm/lib/Transforms/Scalar/LICM.cpp
    llvm/test/Transforms/LICM/gc-relocate.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index 2875b301bbf1..da054c67fe8d 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -1502,8 +1502,8 @@ static Instruction *cloneInstructionInExitBlock(
     }
   }
 
-  // Build LCSSA PHI nodes for any in-loop operands. Note that this is
-  // particularly cheap because we can rip off the PHI node that we're
+  // Build LCSSA PHI nodes for any in-loop operands (if legal).  Note that
+  // this is particularly cheap because we can rip off the PHI node that we're
   // replacing for the number and blocks of the predecessors.
   // OPT: If this shows up in a profile, we can instead finish sinking all
   // invariant instructions, and then walk their operands to re-establish
@@ -1512,7 +1512,7 @@ static Instruction *cloneInstructionInExitBlock(
   for (Use &Op : New->operands())
     if (Instruction *OInst = dyn_cast<Instruction>(Op))
       if (Loop *OLoop = LI->getLoopFor(OInst->getParent()))
-        if (!OLoop->contains(&PN)) {
+        if (!OLoop->contains(&PN) && !Op->getType()->isTokenTy()) {
           PHINode *OpPN =
               PHINode::Create(OInst->getType(), PN.getNumIncomingValues(),
                               OInst->getName() + ".lcssa", &ExitBlock.front());
@@ -1856,10 +1856,13 @@ class LoopPromoter : public LoadAndStorePromoter {
   AAMDNodes AATags;
   ICFLoopSafetyInfo &SafetyInfo;
 
+  // We're about to add a use of V in a loop exit block.  Insert an LCSSA phi
+  // (if legal) if doing so would add an out-of-loop use to an instruction
+  // defined in-loop.
   Value *maybeInsertLCSSAPHI(Value *V, BasicBlock *BB) const {
     if (Instruction *I = dyn_cast<Instruction>(V))
       if (Loop *L = LI.getLoopFor(I->getParent()))
-        if (!L->contains(BB)) {
+        if (!L->contains(BB) && !I->getType()->isTokenTy()) {
           // We need to create an LCSSA PHI node for the incoming value and
           // store that.
           PHINode *PN = PHINode::Create(I->getType(), PredCache.size(BB),

diff  --git a/llvm/test/Transforms/LICM/gc-relocate.ll b/llvm/test/Transforms/LICM/gc-relocate.ll
index ac5c8df47bee..e7498fb51e37 100644
--- a/llvm/test/Transforms/LICM/gc-relocate.ll
+++ b/llvm/test/Transforms/LICM/gc-relocate.ll
@@ -10,18 +10,17 @@ define i8 addrspace(1)* @test(i8 addrspace(1)* %arg) #0 gc "statepoint-example"
 ; CHECK-NEXT:    br label [[BB1:%.*]]
 ; CHECK:       bb1:
 ; CHECK-NEXT:    [[TMP:%.*]] = call token (i64, i32, i32 (i32, i8 addrspace(1)*, i32, i32, i32)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i32i32p1i8i32i32i32f(i64 1, i32 16, i32 (i32, i8 addrspace(1)*, i32, i32, i32)* nonnull @zot, i32 5, i32 0, i32 undef, i8 addrspace(1)* undef, i32 undef, i32 undef, i32 undef, i32 0, i32 0) [ "deopt"(i32 0, i32 0, i32 0, i32 235, i32 3, i32 32, i32 0, i32 0, i8 addrspace(1)* undef, i32 3, i32 undef, i32 3, float undef, i32 0, i8 addrspace(1)* undef, i32 7, i8* null, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 0, i8 addrspace(1)* undef, i32 4, double undef, i32 7, i8* null, i32 0, i8 addrspace(1)* undef, i32 3, float undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* null, i32 3, i32 -15108, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null), "gc-live"(i8 addrspace(1)* [[ARG:%.*]]) ]
-; CHECK-NEXT:    [[RES:%.*]] = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token [[TMP]], i32 0, i32 0)
 ; CHECK-NEXT:    br i1 false, label [[BB1]], label [[BB2:%.*]]
 ; CHECK:       bb2:
-; CHECK-NEXT:    [[RES_LCSSA:%.*]] = phi i8 addrspace(1)* [ [[RES]], [[BB1]] ]
-; CHECK-NEXT:    ret i8 addrspace(1)* [[RES_LCSSA]]
+; CHECK-NEXT:    [[RES_LE:%.*]] = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token [[TMP]], i32 0, i32 0) #[[ATTR2:[0-9]+]]
+; CHECK-NEXT:    ret i8 addrspace(1)* [[RES_LE]]
 ;
 bb:
   br label %bb1
 
 bb1:
   %tmp = call token (i64, i32, i32 (i32, i8 addrspace(1)*, i32, i32, i32)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i32i32p1i8i32i32i32f(i64 1, i32 16, i32 (i32, i8 addrspace(1)*, i32, i32, i32)* nonnull @zot, i32 5, i32 0, i32 undef, i8 addrspace(1)* undef, i32 undef, i32 undef, i32 undef, i32 0, i32 0) [ "deopt"(i32 0, i32 0, i32 0, i32 235, i32 3, i32 32, i32 0, i32 0, i8 addrspace(1)* undef, i32 3, i32 undef, i32 3, float undef, i32 0, i8 addrspace(1)* undef, i32 7, i8* null, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 3, i32 undef, i32 0, i8 addrspace(1)* undef, i32 4, double undef, i32 7, i8* null, i32 0, i8 addrspace(1)* undef, i32 3, float undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* undef, i32 0, i8 addrspace(1)* null, i32 3, i32 -15108, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null, i32 7, i8* null), "gc-live"(i8 addrspace(1)* %arg) ]
-  %res = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %tmp, i32 0, i32 0)
+  %res = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %tmp, i32 0, i32 0) readnone
   br i1 undef, label %bb1, label %bb2
 
 bb2: